The invention concerns a superconducting magnet coil configuration with at least one section containing a superconducting strip conductor which is wound in a cylindrical winding chamber between two end flanges in several solenoid-like layers.
Magnet coil configurations of this type are known in the art.
Notches are frequently used to homogenize compact high field magnets via field correction of magnet coil configurations having low-temperature superconductors (LTS). A conventional notch region is designed by initially completely winding the first notch winding on one side of the notch. The wire is then bent sharply and guided axially through the notch. The second notch winding is then wound on the other side. LTS coils of this type are either not reacted at all (e.g. for use of NbTi superconductors) or are produced in a “wind-and-react” method. In the latter case, the coil is already wound into its final shape with a mechanically insensitive initial filament structure which, in the wound state, is subjected to an annealing process in an atmosphere containing little oxygen. A solid state diffusion procedure is performed during the annealing process to produce the superconducting material (e.g. Nb3Sn). This superconducting material is extremely brittle following the solid state diffusion reaction and cannot be deformed.
The highest field strengths are obtained by using strip conductors of high-temperature superconducting (HTS) material in the innermost magnet coil windings. HTS conductors require a defined oxygen atmosphere during the annealing process. The annealing process is therefore performed before the superconducting wire is wound. The coil is then wound from strip conductors which are already superconducting (“react-and-wind” method). Due to the high mechanical sensitivity of these strip conductors, the notches cannot be conventionally designed in this region. In particular, transfer of the strip conductor from one side of the notch to the other side using the above-described sharp bend and the associated small radius of curvature is not possible with an HTS strip conductor. The mechanical sensitivity of HTS strip conductors is particularly problematic in view of forming a notch region in a magnet coil configuration since damage to the HTS conductor material would result in a costly defect in the overall magnet coil configuration. Undesired inhomogeneities in HTS coils must therefore be compensated for using separate correction coils.
It is therefore the underlying purpose of the invention to propose a magnet coil configuration using HTS material which has a notch structure for correcting inhomogeneities, wherein the mechanical load on the HTS strip conductor is minimized.